- Prinz, Hermann, 1868-1957, author1
- Prothero, James Harrison, author1
- Prunell, A. (Alfredo), author1
- Pyle, William Henry, 1875- author1
- Raiziss, George W., 1884- author1
- Ramon y Cajal, Santiago, 1852-1934, author1
- Ramsey, Walter Reeve, 1872- author1
- Ratcliff, A. J. J. (Arthur James John), 1894- author1
- Read, Lillian, A., author1
- Reed, Charles B. (Charles Bert), 1866- author1
- Reid, E. Priscilla (Elizabeth Priscilla), author1
- Reid, William Duncan, 1885- author1
- Rhode Island. State Board of Health, author.1
- Riley, Henry Alsop, 1887-1966, author1
- Ritchie, John W. (John Woodside), 1871-1943, author1
- Ritter, John, M.D., author1
- Rísquez, Jesús Rafael, author1
- Rogers, L. W. (Louis William), 1859-1953, author1
- Root, Francis M. (Francis Metcalf), 1889-1934, author1
- Rost, Franz, 1884-1935, author1