Should I Open 1NT with a 5-card Major? This is the #1 question. If bridge teachers had a dollar for every time this question is asked, they'd be wealthy people.

Let me start by saying, that there is no "right" answer (which is probably why it keeps getting asked). All you can ask for is an opinion. Well-known teachers such as Zeke Jabbour and Bernie Chazen, prefer to open with the major. Marty Bergen and Roberta Salob will tell you 1NT. No doubt, other famous teachers will weigh in with a strong opinion.

My advice for Intermediates and lower:

With 15-17 balanced, and a 5-card major, open 1NT

(I will give my advice for more advanced players at the end). Meanwhile, the biggest reason I have for opening 1NT is that if you don't open 1NT, you will have a major (pardon the pun) headache when it comes time to rebid. For example, say you hold:

♠ Q 10
♥ A Q 10 4 2
♦ K J 2
♣ K J 3

If you open 1H, what will you do next? Suppose partner answers with 1S. How do you show this hand? If you rebid 1NT, you are showing less than 15 points. If you rebid 2NT, you are showing more than 17. That is why I prefer to start with 1NT. You have 16 balanced and if you open 1H, you will never be able to convey that information. Whatever partner responds to 1H, you will have trouble telling partner that you have 16 HCP.

Is there a downside? Of course. By opening with 1NT, you will sometimes miss out on a proper contract in your major. You will miss some 5-3 major-suit fits (and occasionally, even a 5-4 fit). There are conventions (such as Puppet Stayman) to get out of this mess, but those are outside the scope of this article.

I have found (in 30+ years) of experience, that my way is the best way. I have my good and bad moments, but in the long run, the money goes to the 1NT opening. Even when I do miss a 5-3 major-suit fit, I find that notrump plays just as well (and even if it is the same, it is worth a fortune at matchpoints to get the 10 extra points for your contract).

I think it best for less-experienced players to blindly open all balanced 15-17 hands with 1NT. That is because opening with the major ends up creating annoying rebid problems. For example, players that open the hand above with 1H, will have to invent a rebid (typically in a 3-card suit). Bridge is hard enough. Intermediate players need to keep things simple.

For more expert/experienced players:

However, if you are willing to have an adventure or two, I suggest that you don't "blindly" open 1NT on every 15-17 balanced hand. For example, consider:

♠ 3 2
♥ A K Q J 10
♦ A J 10
♣ 4 3 2

This is obviously a "loaded" hand, but even I wouldn't open 1NT. I'd start with 1H, and try to cope later. The stoppers are bad for notrump, and it just doesn't look like a notrump. On the other hand, if I had this flawed collection:

♠  A J 2
♥ K Q 8 4 2
♦  K Q
♣ 10 5 2

I would start with 1NT. There are many factors, but one is that I have three spades, so if partner happens to transfer to spades, I'll be content. (If it is close, and I have only a doubleton in one major, I might lean towards opening in the other major). If I have 2 suits totally unstopped, I also would tend to open the major. In general, though, I open almost all balanced 15-17 hands with 1NT. (One big payoff comes when LHO leads 4th best against notrump into your undisclosed five-card major!).

Some teachers say to go one way with hearts, another way with spades. Others say to "shade" your hand and treat it as 14 or 18 (thereby having no rebid problem). If you wish to have lots of rules, and use lots of judgment, then by all means have a ball and switch back and forth.

For most players, though, I think simple is best. With 15-17 balanced, open 1NT.