A capsule (10) of, for instance, hard gelatin for holding a substance such as medicine, food supplements or similar materials includes a capsule body (44) having a closed and an opposed open end with a predetermined length defined between the ends. A diaphragm (50) having a closed end and an opposed open end and a predetermined length there between seals off the body (44) and provides a first compartment (48) to hold a first medicine, food supplement, etc. A cap (60) is applied to the body (44) as is conventional in capsules. The space between the inner portion of the cap (60) and the diaphragm (50) defines a second compartment (64) for holding a second medicine, food supplement, etc. The contents of each compartment (48,64) may be wet or dry (e.g., powder or liquid.) This two-compartment capsule has particular relationships between the length along an axis of the capsule of the diaphragm (50) to that of the body (44), and particular dimensional parameters relating to the sidewall contact seal between the outer portion of the diaphragm (50) and the inner wall of the body (44), to provide adequate capsule sealing and stability during and after manufacture.