A medical journal was a publications that detailed advances and research in the field of medicine.
The planet Malcor III's medical journals had documented several instances of genetic mutations as of 2367. Attempting to preserve his alias of Rivas Jakara, William T. Riker suggested to Berel that he (Jakara) might be another case for the medical journals. The physician conceded the possibility, but still felt Jakara was hiding something. (TNG: "First Contact")
In 2370, upon seeing Melora Pazlar able to walk despite Deep Space 9's gravity settings, Miles O'Brien assured Doctor Julian Bashir that the feat would get Bashir's name into the medical journals. (DS9: "Melora")