Par 1 Maryla Jonas, Polish pianist whose Carnegie Hall debut in 1946 established her in the front rank of contemporary pianists, returned to the same hall yesterday after an absence of five years.

Par 2 It was known that Miss Jonas had been ill for four years with a blood infection. Her recovery and the resumption of her concert career were announced last year. But there were admirers in the audience yesterday afternoon who feared that she might not have won back the necessary strength for the ordeal of a Carnegie Hall concert.

Par 3 The first half of Miss Jonas' program was devoted to Mozart, the second to Chopin. She began the opening Mozart Sonata (K. 330) brilliantly, a trifle too brilliantly, like an artist who controls the notes but is not yet enough at ease to give the music warmth.

Par 4 This lack passed quickly, however, and by the time she reached the development section of the sonata's first movement she was playing, or rather singing, the phrases with a sensitivity and glow such as one rarely hears today, even among players of the front rank.

Par 5 The Andante cantabile of the middle movement too was an achievement of rare artistry. But toward the end of the sonata Miss Jonas began to sound nervous. As the Mozart group progressed there were moments of exquisite lyricism, but they became rarer as one sensed that Miss Jonas' strength was ebbing under physical and nervous strain.

Par 6 Miss Jonas is too skilled a musician to allow momentary lapses of memory to show openly, but before she finished she had been forced to leave out whole sections of certain works and omit others altogether.

Par 7 One charming Chopin work she did play was the early "Souvenier [Souvenir] de Paganini," announced as a first performance in New York. She played only part of the "Grand Polonaise" in F sharp minor, which completed the program.

Par 8 Friends who inquired backstage after the program were told that a physician was attending Miss Jonas. Later it was announced that she was not ill but suffered only severe nervous tension.