- Pyarthritis - see Pyarthrosis
- Pyarthrosis (see also Arthritis, pyogenic) 711.0
- Pycnoepilepsy, pycnolepsy (idiopathic) (see also Epilepsy) 345.0
- Pyelectasia 593.89
- Pyelectasis 593.89
- Pyelitis (congenital) (uremic) 590.80
- Pyelo-ureteritis cystica 590.3
- Pyelocaliectasis 593.89
- Pyelocystitis (see also Pyelitis) 590.80
- Pyelohydronephrosis 591
- Pyelonephritis (see also Pyelitis) 590.80
- Pyelonephrosis (see also Pyelitis) 590.80
- Pyelophlebitis 451.89
- Pyemia, pyemic (purulent) (see also Septicemia) 038.9
- Pygopagus 759.4
- Pykno-epilepsy, pyknolepsy (idiopathic) (see also Epilepsy) 345.0
- Pyle (-Cohn) disease (craniometaphyseal dysplasia) 756.89
- Pylephlebitis (suppurative) 572.1
- Pylethrombophlebitis 572.1
- Pylethrombosis 572.1
- Pyloritis (see also Gastritis) 535.5
- Pylorospasm (reflex) 537.81