  We explore the connection between pentaquarks and dibaryons composed of three
diquarks in the framework of the diquark model. With the available experimental
data on H dibaryon, we estimate the Pauli blocking and annihilation effects and
constrain the $P=-$ pentaquark $SU(3)_F$ singlet mass. Using the $\Theta^+$
pentaquark mass, we estimate $P=-$ dibaryon mass.
