Since the American Academy of Pediatrics (AAP) and the International Electrotechnical Commission (IEC) upheld the criterion of effective irradiated area as part of design standards for neonatal phototherapy lamps, it has become a very important factor to guarantee according to a certain method a uniform distribution of irradiance besides an effective phototherapy treatment. The objective of this article is show through an analytical method the most uniform distribution of irradiance with a matrix of blue LEDs. Besides the proposed design is simulated in a specialized software and evaluated experimentally for its respective validation. Irradiance tests are included with a calibrated radiometer.