Yes, you can. I think you are talking about urine pregnancy test. Yes, you can get positive in the morning and negative in the evening. The reason is the urine in the morning, in the early morning if you have mot passed in the midnight, in the morning it is concentrated. So the pregnancy hormone, Beta Hcg is at a higher level in the morning urine. So it should give a positive test and sometimes in the evening as the day goes on, you take a lot of fluids, beverages, your urine gets diluted. So the hormone levels may fall and then you may get a negative test. So this is perfectly possible. So you get a positive test in the morning and a negative test in the evening. So always do your urine pregnancy test in the early morning.